Caffeine In Drinks Potentially Addictive, Researchers Show

The caffeine in coffee, tea and cola can produce addiction similar to that engendered by alcohol, tobacco, heroin and cocaine, researchers from Johns Hopkins University reported today.

Although abruptly halting intake of caffeine has long been known to trigger withdrawal symptoms that include headaches, lethargy and depression, the new report in the Journal of the American Medical Association suggests that the drug produces the full range of symptoms associated with classical psychoactive dependence.

In addition to withdrawal, those symptoms include persistent, unsuccessful efforts to reduce consumption, continued use despite medical side effects and tolerance, and a need for ever-higher doses to achieve the same psychological effects.

Some evidence, furthermore, suggests that the prevalence of dependence on caffeine is about the same as for alcohol - about 14 percent of users - according to an editorial by Dr. Richard M. Glass of the JAMA staff.

The researchers undertook the study "because there are some people who have problems with caffeine use and are distressed by it," said Dr. Eric Strain, the Johns Hopkins psychiatrist who co-authored the study. "It is helpful because it shows us that caffeine is a drug like other drugs and in terms of understanding the whole addiction process," he said.

Although caffeine can cause symptoms such as sleeplessness and anxiety, he noted that it has far fewer ill effects than other addictive drugs like nicotine, alcohol, heroin and cocaine, so that the significance of addiction to it is not yet clear. "This doesn't mean that people have to stop drinking coffee," Strain said.

Nevertheless, the results led Dr. John Hughes of the University of Vermont to suggest that, "Perhaps we should start labeling coffee to indicate its addictive potential. That's something I'd like to know as a consumer."

Fully 80 percent of adult Americans consume caffeine regularly, with an average daily dose of about 280 milligrams. A 5-ounce cup of coffee or tea contains about 100 milligrams of caffeine, while a 12-ounce cola contains about 60. Chocolate drinks and chocolate candy also contain caffeine, but much less.

Strain and his colleagues ran newspaper advertisements soliciting people who thought they were dependent on caffeine. Telephone interviews of 99 respondents identified 27, ranging in age from 21 to 48, who were willing to visit the laboratory twice, undergo medical and psychiatric interviews and keep a detailed food diary for a week.

Examining the 27 subjects, the team found that 94 percent displayed withdrawal symptoms when they did not use caffeine, and 94 percent continued caffeine use despite medical contraindications. Some 81 percent had made unsuccessful efforts to cut down on caffeine use, while 75 percent needed increasing amounts.

In a news release from the International Food Information Council, a trade group, Dr. Peter Dews of Harvard Medical School said that "This study ... adds nothing of relevance to normal people consuming caffeine."He said some study participants had a history of substance abuse.